Numerical and experimental study of meandering electrode for photodiode bandwidth enhancement

Bandwidth enhancement for avalanche photodiodes (APDs) has been a focal point of research. This paper designs, fabricates and demonstrates a novel meandering coplanar waveguide electrode to effectively introduce the inductive peaking effect into APDs, resonating with internal capacitance to enhance bandwidth. Initially, an analytical model is employed to scrutinize the influence of the inductance peaking effect on the photodiode bandwidth. Various dimensions of meandering electrodes are simulated and optimized to introduce suitable inductance values into APDs. Fabricated APDs with different electrodes show measured results consistent with simulations. Compared to conventional 50Ω electrodes, the meandering electrode significantly increases the bandwidth of APDs from 8.5 GHz to over 15 GHz. Lastly, a detailed analysis of the APD measured results is conducted using an equivalent circuit model, the inductance introduced by the proposed electrode is approximately 980 pH. This study can extend to other types of photodiode, offering a novel and effective high-performance photodiode design method.